1. Field of the Invention
This invention relates generally to electronically filtered connectors, and more particularly to filtered adapter assemblies and filtered jacks in a coaxial configuration.
2. Description of the Prior Art
Electronic filters are well-known within the industry and are used to selectively attenuate certain signals in transmission lines by shunting unwanted signal frequencies to ground. Typically, such filters are of a fragile ceramic construction and as such have heretofore been difficult to incorporate into a coaxially configured connector design. Consequently, many coaxial connectors are used in the field in applications which should, but do not, have filter elements for filtering out unwanted electromagnetic interference. Specifically, the industry is in need of a coaxial filtered adapter for retrofitting mating coaxial connector units with a filtering capability. Prospectively, the industry is in need of a filtered jack assembly as an interface to instruments requiring filter protection.
One problem has been how to mechanically insulate the filter within an adapter from externally originating forces which would crack the filter causing a malfunction. Isolation of the filter sleeve, however, can not be attained at the sacrifice of good electrical contact between the filter and the adapter shell, for positive grounding contact is imperative in any filterized coaxial adapter approach. Moreover, from an ecomonic standpoint, it is desirable that any filtered adapter have a minimal number of parts to facilitate ease of assembly, and the adapter parts should be standardized as much as possible to reduce cost. Standardization of adapter parts is difficult because a coaxial adapter must accommodate receipt of filters of varying size since different electronic applications require the use of filters of differing lengths.
The industry's effort to resolve the above heretofore irreconcilable constraints on any proposed coaxial filtered adapter have met with mixed results. One connector approach is disclosed in U.S. Pat. No. 4,029,386, and comprises a plastic metal-coated ground wafer having integral tines for engaging filtered terminals encapsulated within elastomeric inserts. While this connector works well and has been well received by the industry, certain problems attendant upon its use prevent the connector from representing an ideal solution. As stated above, mechanical insulation of a filter sleeve within a connector or adapter must be provided, and positive contact between an adapter shell and the filter therein beyond that achieved by a tine configuration is required.